From: Zachary Amsden <zach@vmware.com>
To: Andi Kleen <ak@suse.de>
Cc: Virtualization Mailing List <virtualization@lists.osdl.org>
Subject: Re: Why disable vdso by default with CONFIG_PARAVIRT?
Date: Mon, 11 Dec 2006 22:28:42 -0800 [thread overview]
Message-ID: <457E4C1A.4000905@vmware.com> (raw)
In-Reply-To: <200612120402.19958.ak@suse.de>
Andi Kleen wrote:
> On Tuesday 12 December 2006 02:22, Jeremy Fitzhardinge wrote:
>
>> What problem do they cause together? There's certainly no problem with
>> Xen+vdso
>>
>
> This was the change which finally got my test system (with an older
> SUSE 9.0 based user land to boot). With paravirt older glibc's ld.so
> otherwise throws assertation failures because it somehow can't deal with
> the new placement. This only happens with paravirt enabled.
>
> Binary compatibility is important.
>
Yes, but the old placement of the vdso is incompatible with paravirt
guests. The only solution I can think of to keep compatibility is to
dynamically place the vdso during boot, but this is complex and
introduces an indirection penalty to the fast sysenter syscall path
(unless we make that a dynamic patch).
What should we do to fix this? Breaking compatibility for paravirt
compilation is certainly the easiest thing to do.
Zach
next prev parent reply other threads:[~2006-12-12 6:28 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-12 1:22 Why disable vdso by default with CONFIG_PARAVIRT? Jeremy Fitzhardinge
2006-12-12 1:42 ` Zachary Amsden
2006-12-12 1:44 ` Jeremy Fitzhardinge
2006-12-12 1:46 ` Zachary Amsden
2006-12-12 1:49 ` Jeremy Fitzhardinge
2006-12-12 3:02 ` Andi Kleen
2006-12-12 6:28 ` Zachary Amsden [this message]
2006-12-12 6:50 ` Jeremy Fitzhardinge
2006-12-12 7:27 ` Andi Kleen
2006-12-12 10:23 ` Jeremy Fitzhardinge
2006-12-12 12:01 ` Andi Kleen
2006-12-12 20:11 ` Jeremy Fitzhardinge
2006-12-12 21:15 ` Andi Kleen
2006-12-13 2:04 ` Rusty Russell
2006-12-13 4:36 ` Rusty Russell
2006-12-13 5:25 ` Rusty Russell
2006-12-12 23:22 ` Rusty Russell
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